1. Field of the Invention
The present invention relates to a packaged semiconductor and a process for manufacturing the packaged semiconductor.
2. Description of the Related Art
A conventional packaged semiconductor 10 is, as shown in FIG. 10, provided with a package 14 in which a semiconductor device (not shown) mounted on an island (not shown) and a part of a lead frame 12 (see FIG. 7) are sealed with a resin and a plurality of leads 12a extending from the side of the package 14.
As shown in FIG. 7, each lead 12a is formed by punching the lead frame 12. The leads 12a are connected to each other by tie bars A2 and each outside lead 12a is connected to the lead frame 12 by a tie bar B2.
Dam bars (also called xe2x80x9ctie barsxe2x80x9d) Al having the function of blocking the flow of the resin during the molding of the package 14 are used to connect the leads 12a to each other and each lead 12a with the lead frame 12. Also, the island is connected to the lead frame 12 through an island support pins 18.
A plurality of guide holes 20 which are openings used for positioning during the process of bending the leads 12a are formed in the lead frame 12. It is to be noted that the material generally used for the lead frame 12 is a 42 alloy (Fe, Ni) or a copper alloy with a plate thickness of approximately 0.15 mm.
The surface of the molded lead frame 12 (including the lead 12a) is provided with solder plating through electrical connection of the lead frame 12 to an external section. In the solder plating method, as shown in FIG. 11, the lead frame 12 and a solder electrode 11 (anode) are dipped in an acidic electrolyte 13 (solder plating bath) in which Sn and Pb have been dissolved as solder components in advance and are electrically connected to each other and energized, thereby electrodepositing solder (Sn and Pb) on the surface of the lead frame 12 (cathode).
After the solder plating is finished, the lead 12a is processed into a predetermined shape. Specifically, in the step of processing the lead 12a, as shown in FIG. 7 and FIG. 8, all dam bars A1 are punched and next the tie bars B2 at both ends are punched using a metal mold. Thereafter bending of the lead 12a is performed.
This bending of the leads 12a is carried out using a forming die 22 as shown in FIG. 9. Namely, the lead frame 12 is automatically conveyed to and placed on a bending die 24 of the forming die 22 and an upper die 25 is allowed to descend. At this time, the pilot pin 26 mates with the guide hole 20 to position the lead frame 12. Next, the leads 12a disposed in the vicinity of the package 14 are sandwiched between a knockout 28 pushed by a spring 30 and the bending die 24. Thereafter, as shown in FIG. 8 and FIG. 9, the bending punch 32 is lowered so as to push down the end of each lead 12a, thereby performing the bending.
Next, the end portion of each lead 12a which includes the tie bar A2 is cut and the island support pins 18 are cut off from the lead frame 12 to complete the manufacture of the packaged semiconductor 10 shown in FIG. 10.
In the above bending process using a forming die, however, the solder plating on the surface of the lead is rubbed by the bending punch during the processing and the rubbed off solder plating is pressed against and laminated on the punching surface of the bending punch to create solder residue.
Moreover, this solder residue then comes off the punching surface of the bending punch during the bending of the lead and adheres again to the surface of the lead.
As a consequence, the above bending causes short circuiting between the leads as well as a deteriorated appearance, giving rise to serious problems in the quality of the product.
It is therefore necessary that the operation of the apparatus be frequently suspended to clean the forming die, remarkably impairing the production efficiency of the packaged semiconductor.
In light of the above problem, an object of the present invention is to provide a packaged semiconductor produced by performing solder plating after the bending of the leads has been completed so that no solder residue is created. Another object of the present invention is to provide a process for manufacturing a packaged semiconductor. According to a first aspect of the present invention, there is provided a packaged semiconductor comprising:
a semiconductor having a plurality of leads extending therefrom, the leads having been formed by mounting the semiconductor device in a lead frame and punching and sealing the leads in the semiconductor device using a resin, wherein the leads have been bent to a predetermined configuration; and
connecting means for connecting said leads to said frame, said connecting means being bent substantially simultaneously as when said leads are bent to the predetermined configuration.
According to this structure, the lead frame is connected to the leads by the connecting means in the packaged semiconductor produced by processing the lead frame by punching in order to form the plurality of leads and by mounting the semiconductor device on the lead frame and then sealing it with resin. This connecting means is bent at the same time the leads are bent. Hence a connection can be maintained between the leads and the lead frame after the bending of the leads is finished.
According to another aspect of the present invention, there is provided a process for manufacturing a packaged semiconductor, comprising the steps of:
mounting a semiconductor device having leads in a lead frame by using connecting means to connect the semiconductor device to the lead frame;
sealing said semiconductor device using a resin;
bending the leads of the semiconductor device to a predetermined configuration and substantially simultaneously bending the connecting means;
dipping said lead frame and a solder electrode in an acidic electrolyte to connect said lead frame to said solder electrode electrically thereby coating the surface of said leads with solder plating; and thereafter
disconnecting the connection made by said connecting means.
According to this process, the packaged semiconductor provided with a package in which a semiconductor device is mounted on a lead frame in which a plurality of leads have been formed by punching and which is sealed using a resin, wherein the leads extending from the side of the package are formed by bending, is manufactured by the first to fourth steps given below.
Specifically, in the first step, the lead frame and the semiconductor device are sealed with a resin to form a package.
In the second step, the connecting means which connects the lead to the lead frame is bent at the same time the lead is bent.
In the third step, the lead frame and the solder electrode are dipped in the acidic electrolyte and the lead frame is electrically connected to the solder electrode to provide the surface of the lead with solder plating.
Finally, in the fourth step, the connection made by the connecting means is terminated.
The production of a packaged semiconductor according to the above manufacturing process ensures that since solder plating can be provided on the surface of the lead after the lead is bent, the solder plating formed on the surface of the lead does not peel off and no solder residue is produced.
According to another aspect of the present invention, there is provided a device for forming a packaged semiconductor, the device comprising:
a semiconductor having a plurality of leads extending therefrom;
a lead frame in which the semiconductor device is mounted; and
an elongated connection member having opposite longitudinal edges, with one longitudinal edge connected to the lead frame and the opposite longitudinal edge connected to a lead of the semiconductor device.